Shimmura, A.1, Inui, T.1, Yamaguchi, Y.1, Oshita, K.1 and Hideshima, S.1, (1)Suntory Beer Limited, Research & Development Center for Liquors, Shimamoto-cho, Mishima-gun, JAPAN
Technical Session 3: Analytical Flavors
Monday, June 05, 2017
8:30–10:15 a.m.
Caloosa Ballroom
Barrel-aged beer having a peculiar flavor originating from the wood are attracting attention not only in its birthplace (Belgium and Germany), but also in the United States, as well as micro-breweries in Japan. Various parameters, such as wood origin, the history of the barrel, aging time, toasting condition, and the type of beer aged in the barrel could exert influence on the flavor characteristics and intensities of barrel-aged beer. Among these parameters, the relationship between aging time and flavor of barrel-aged beer was especially focused on in this research. Comparison of sensory evaluation and compound analysis between beer samples with different aging times were implemented to control barrel-aged beer flavor. It was confirmed that there were significant differences between beer samples with different aging times from 0 to 24 weeks. The initial aging time (0–4 weeks) had slight changes in flavor characteristics, although after 4 weeks, there were remarkable changes in flavor profiles of beer. It was assumed that compounds relating to flavor characteristics that were extracted from the barrel don’t easily dissolve into the beer in a comparably short aging time, and an obvious barrel-aged flavor could be obtained by aging for a longer time. At first, six flavor attributes of barrel-aged beer were extracted by comparing beers between before and after barrel-aging. Those were fullness, coconut-like, vanilla-like, woody, phenolic, and oxidized malty, and were scored. To examine the compound profile relating to flavor attributes, sensory analysis adding fractions of aroma compounds extracted from barrel-aged beer that were discriminated by polarity were implemented. As a comprehensive chemical analysis, sniffing-GC and GC×GC-TOF/MS of fractions that especially contributed to typical barrel-aged flavor were implemented. The key compounds were identified, and the behavior of those during aging time were examined. Barrel-aged flavor could be perceived even though the aging time is 0 to 4 weeks, and the score of coconut-like and vanilla-like were comparably high. On the other hand, after 4 weeks, the score of coconut-like and vanilla-like were low, and that of oxidized malty and phenolic were high. As a result of compound analysis, characteristic compounds could be narrowed down to 10, including γ-octanolactone and γ-nonalactone, which are wood’s volatile oil compounds, besides vanillin, a compound yielded by the heat decomposition of lignin, which is one of the major structural compounds of wood. By evaluating the quantitative data of the behavior of these compounds during aging , 4-ethylguaiacol having a phenolic feature was minimized (below 1.2 µg/L) when the aging time was 0 to 4 weeks, and increased remarkably after 4 weeks. Trans-oak lactone, which has a sweet coconut feature, could be perceived (30 µg/L) within 4 weeks. These results corresponded well to the sensory evaluation scores. In conclusion, it was confirmed that controlling of the aging time enables big changes in flavor of barrel-aged beer.
Anna Shimmura graduated from Osaka University with a master’s degree of chemical engineering in 2014. After joining Suntory, she worked for three years in the Beer Development Department of Suntory Beer Limited. She is engaged in research on the development of brewing technology and flavor science of beers, such as barrel-aged beer and beer using colored malts.
